The Ralstonia solanacearum species complex includes thousands of strains pathogenic to an unusually wide range of plants. The genome of R. solananearum complex strains is organized into two replicons, a chromosome and a megaplasmid. Strains within this ancient species complex can be subdivided into four phylotypes, corresponding to strains from Asia (phylotype I), the Americas (phylotype II), Africa (phylotype III) and Indonesia (phylotype IV)1. Previous phylogenetic studies indicate greater than 30% divergence among strains despite an apparently common mode of pathogenesis. Comparison of genome sequences of R. solanacearum strains representative of this phylogenetic diversity can help determine which traits allow this bacterium to be such an aggressive and lethal pathogen of so many different plant species and how the bacteria survive in many different habitats such as soil, water, non-host plant rhizospheres and host xylem vessels. We used comparative genomic analysis to explore the diversity of three strains of R. solanacearum all of which are able to cause bacterial wilt of tomato. R. solanacearum strains CFBP2957 (phylotype IIA), CMR15 (phylotype III) and PSI07 (phylotype IV) were isolated in the Caribbean, Cameroon, and Indonesia, respectively. The bipartite genomes of these three strains were manual annotated and the genomes were compared with those of previously sequenced R. solanacearum strains GMI1000 (phylotype I)2, Molk2 (phylotype IIB) and IPO1609 (phylotype IIB)3. Comparative genomic analyses were completed using a comparative genomic hybridization (CGH) microarray on a larger set of R. solanacearum strains. The major genomic features were conserved across all of the six strains for which genomic sequences were available and the organisation of genomes was highly syntenic. Comparative analysis of genome sequences and gene content confirmed the differentiation of R. solanacearum species complex strains into the four phylotypes. The genomic